Traveller sites tend to be associated with increased levels of crime, violence, anti-social behaviour, illegal dumping and burning.
That's according to the County and City Management Association, which represents local authorities.
It'll tell an Oireachtas committee today these issues may be behind objections to more Traveller accommodation.
Fianna Fáil TD Eamon Ó Cuiv chairs the committee - he says the comments are unfair.